1. Field of the Invention
The invention relates to a wiring substrate on which metal wires are formed.
2. Description of Related Art
Wiring substrates are used in many products, including OA equipment such as personal computers, printers, scanners, and various types of memory; household appliances such as television sets, audio equipment, cleaners, refrigerators, microwave ovens, and rice cookers; and transportation means such as automobiles, trains, ships, and airplanes. Metal wires are formed on such wiring substrates, and LSIs, ICs, transistors, diodes, capacitors, and resistors, for example, are mounted in accordance with the metal wires.
While the wiring substrates are in many cases formed by plating, methods have recently been disclosed whereby metal wires are formed by drawing or depicting them using a dispersion liquid of metal microparticles and then subjecting the drawn wires to heating or other processes. Examples of the relevant methods are disclosed in Patent Documents 1 to 3, whereby a substrate is coated with a dispersion liquid of metal microparticles using an ink-jet head and therefore no masks or the like are required. Since these methods enable wires to be directly drawn on the substrate using a dispersion liquid of metal microparticles, they are suitable for the manufacture of a wide variety of wiring substrates in small quantities.    Patent Document 1: JP Patent Publication (Kokai) No. 10-204350 A (1998)    Patent Document 2: JP Patent Publication (Kokai) No. 2002-134878 A    Patent Document 3: JP Patent Publication (Kokai) No. 2002-324966 A    Non-Patent Document 1: Nikkei Electronics, Jun. 17, 2002, p. 78